Contacting device for electrical measuring and indicating instruments.



E. HAAGN.

CONTACTING DEVICE FOR ELECTRICAL MEASURING AND INDIGATING INSTRUMENTS.

APPLICATION FILED DEC. 21, 1907. 1 ,OO4,420, Patented Sept. 26, 1911.

" nimsr nAnGN, or HANAU, GERMANY, As'sIGNoR To THE-FIRM or o. HEBAEuspoF 1 HANAU, GERMANY.-

oon'mc'rine-nnvrcn FOR ELECTRICAL MEASURING'AND rnnronrmc' rnsmnnivrnnrs.

To all whom 'it may concern:

' Be it known that'I, ERNST HAAGN, a subject of the German Emperor, and resident of Hanau-on-the-Main, Germany, have invent+ ed certain new and useful Improvements in Contacting Devices for Electrical Measuring and Indicating Instruments, of which f the following is a specification.

In electrical measuring instruments 1t is often desirable to provide an indicator wh ch will indicate when the quantity'measured reach'es a certain value or falls above and below a certain value. This is generally ac.- .complished by providingthe movable ele-' ment of the instrument, and more specifically the pointer connected thereto, with a contact which cooperates with a stationary "contact and which closes an indicator circuit. Since the movement of the pointer is however exceedingly slow at times, thereby causing the contacts to gradually approach and separate, it will be seenthat arcing will;

take place even if the current is low, causing the contacts to corrode and adhere. In view 'of the fact that the movable element is necessarily delicate this corrosion and adherence will not only seriously affect the sensitiveness of the instrument, but will also render the'instrument inaccurate just at the point where accuracy is most desired, namely, the indicated point.

The objects of this invention are therefore to construct an instrument which willnot be open to these objectionable featureand which will avoid all adherence and corrosion of the contacts. 1

' dicating circuit containing the contacts is In accordance with this invention the-instrument is so constructed that when the inclosed it is immediately and quickl opened rat another point and the movable 'e ement is given an impulse so as to move the contacts away from each other. In order to provide additional security against arcing the indicator is in a local circuit which is closed by the contact circuit.

The invention willnow be described in connection-with the accompanying drawings,

M of the instrument and has secured to it so as to move therewith a pointer P which -moves over a scale, as shown in the diagram.

The DArsonval type of-instrument is well known'and so it is unnecessary to describe it in detail, but the invention is not necessarily lifnited to this specific type of-measuring instrument; It is often desirable to indicate when the pointer P reaches-a certain point on the scale, or, in other words,'when the measured quantity reache'sa certain value.- The instrument is therefore provided with a Specification of Letters Patent. Pat t d ept 2 1911, Application filed December 21, 1907. Serial No.'40f7,480.

stationary contact 0 which is arranged to be engaged by a wiping movable contact D connected to the movable element of the "instru .ment and, preferably, to the pointer P as shown. The contacts are connected in circuit with a suitable indicator so that the cooperation of these contacts will close the indicator'circuit and notify the attendant. It

will however be seen that the breaking of the contact Will' cause an arc since the'movements of'the pointer are often exceedingly slow when the increase or decrease of the current voltage, etc., is slow. This results in the corrosion and adherence of the contacts even though the current be small, since the accumulative effects will necessarily in time result in damaging or rou'ghening the cooperating surfaces of the contacts. a

A transformer T has its primary connected in-circuit with the contacts and its 'sec- .ondary in parallel with the movable element of the instrument. The secondary isof high resistance so as to limit the current flow through it and not toafi'ect the reading of sisting of a .bell or other suitable indicator B,-and magnet or relay windings 2 and 3 are connected across the terminals of the battery S. A switch R is arranged to close both circuits and the circuit of'2 and 3 is arranged to be'opened by an auxiliary switch A. The switch G is controlled by the magnet 3 which is arranged to attract the armature E carrying one of the contacts of the switch, the switch being normally held closed by a spring, as shown .in; the drawing. The

, .switch It is, arranged to be closed by the magnet winding 1, which, attracts the armature F, carrying one of the contacts of the switch and the switch is normally held open a spring as' shown in the drawing. The

magnet' winding 2 is also arranged to attract I ''tl 1e armature F to hold the switch It closed.

' The parts of the instrument are normally in the position shown in the drawing. If 1 0 contacts C and D. will cooperate to close the thecurrent rises to the indicatedvalue the contact circuit. This will cause the current from the battery S to "flow from the left hand terminal, through-the pointer P, to

contact D, to contact C, through the primary of the transformer T, through the switch G,

andthrough themagnetwwindi-ng .1, back to the. right-hand; terminal -of the battery. This Wlll cause the magnet or relay winding 1 to become energized: so as to close the switch R, therebyclosing the local circuits lncludlng the indicator and the windings 2 after thecircuit through winding 1 has been broken. The closing of the contacts C, D, and the passage of the current through the primary of the transformer '1 will cause a secondary current to be induced in the secondary of the transformer. The connections are so made that the polarity of the secondary current is in a direction opposite to the line or measured current through the movable element when the circuit in the primary is made so that this movable element will be given an impulse to quickly separatev the contacts and thereby furnish additional security for the prevention of arcing and corrosion at the contacts] C, D. Whenv the pointer swings back after the impulse has been iven to it, and after the current in the secon ary of the transformer. has died out, and the circuit through 0, D has been broken atG, no further arcing can take place. After the mechanism has been set in o eration to operate the indicator B, the coal circuit of the indicator ,will remain closed until the attendant opens the switch A.

It will thus be seen that this invention attains the desired objects. The circuit through the 'contacts'C and-D is brokenby an auxiliary switch G and a movement is.

transmitted to. the movable element of the instrument-so as to quickl separate the contacts, and the current is rther maintained at a. low value by placing the indicatorin a local circuit, the resistance of the contact circuit being made large enough so that the current will be held down to a small value. This has the additional advantage that the indicator can be maintained in operation so that it will keep the bell ringing or keep every'indicator device in position until the attendant is notified.

I claim 1. An electrical measuring and indicating instrument comprising in combination, a movable measuring element, a contact carried thereby, ajcooperating stationary con tact, an electrical circuit including said contacts, an indicator, means in said circuit for operating said indicator, and means operating by the closing of said contacts for transmitting an impulse to said -m ovable element so asto separate said contacts.

2. In an electrical measuring and indicating instrument, the combination with the movable element, of a contact carried thereby, 'acooperating stationary contact, an electrical; circuit includin said contacts, an indicator, means in, sai circuit for-operating said indicator, and. inductively operated means acting upon the movable elementto move the same so as to separate said contacts, said means being. set-in operation by the closing of said contacts.

, 3.111 an "electricalmeasuring and indi-, cating instrument, the'combination with the current carrying means of the instrument including a movable element, of a contact carried thereby, a cooperating stationary contact, an indicator, means connected in a circuit .with said contacts for operating the said indicator, and a transformer havin its primary connected in said circuit an its secondary in circuit with the current carrying means. i

4. In an electricalmeasuring and indicatin instrument, the combination with the mova le element, of a contact carried thereby, a cooperating stationarycontact, and a transformer having; its primary connected in a c rcuit withsaid contacts and 1tssec- 'ondary, in circuit with said moving element, 5

5. Inanelectrical measuring and indicate ing instrument, the combination with the current carrying means of the instrument in- 4 eluding a movable element, of a contact carried thereby, a cooperating stationary'contact, a. transformer comprising a primary connected in a circuit with said contacts, and ail-high resistance secondaryv connected in shunt with the current. carrying means, and connections whereby the current flowing in said secondary opposes the measured current.

'6. In 'an electrical measuring and indicat ing instrument, the combination with the movable element, of a contact carried thereby, a cooperating stationary contact,-an elec-- trical circuit including said contacts, an indicator, means connected in said circuit for operating said indicator, and means operating by the closing of said contacts for opening said circuit and for transmitting an impulse to said movable element to separate said contacts.

7. In an electrical measuring and indicating instrument, the combination with the movable element, of a contact carried thereby, a cooperating stationary contact, an electrical circuit including said contacts, an indicator, means connected in said circuit for operating said indicator, and means-operatingby the closing of said contacts for opening said circuit.

8. In an electrical measuring and indicating instrument the combination with the movable element, of a contact carried thereby, .a cooperating stationary contact, an electrical circuit including said contacts, an indicator, means connected in said circuit for operating said indicator, means for maintaining said indicator in operation independent of said circuit, and means operating by the closing of said contacts for opening said circuit.

9. In an electrical measuring and indicating instrument, the combination with themovable element,- of a contact carried thereby, a cooperating stationary element, an electrical circuit including said contacts, an indicator, means connected in said circuit for operating said indicator, a transformer having its primary connected in saidcircuit and its secondary in circuit with the instrument, and means for opening said circuit including said contacts when said contacts are closed.-

10, In an electrical measuring and indicating instrument, the combination with the movable element, of a contact carried thereby, a cooperating stationary element, an electrical circuit including said contacts, an indicator, a local circuit for operating said indicator, an electro-magnet in said contact circuit for closing the local circuit, and electro-magnets in said local circuit, one for maintaining said local circuit closed and another for opening said contact circuit.

11. An electrical measuring and indicating instrument comprising a movable element including a coil, a transformer having its secondary winding connected with the coil of the movable element, a relatively stationary contact, a circuit including said contact and the primary winding of the transformer, a pointer connected to be moved by the movable element to and from said contact and having a contact which is included in the circuit containing the primary winding of the transformer, and an indicator controlled by the circuit including the primary winding of the transformer.

12. An electrical measuring and indicating instrument comprising a movable element including a coil, a transformer having its secondary winding connected with the coil of the movable element, arelatively stationary contact, a circuit including said contact and the primary winding of the transformer, a pointer movable by the movable element to and from said contact and having a contact which is included in the circuit containing the primary winding 'of the transformer, a bellcircuit including a movable member, a coil in the circuit including the primary winding of the transformer, adapted to adjust said movable member of the bell circuit to close the last said circuit means in said bell circuit for breaking the primary winding of the transformer when the bell circuit is closed, a supplemental means for maintaining the bell circuit closed after the circuit including the primary winding of the transformer is broken.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

ERNST HAAGN.

Witnesses JEAN GRUND, CARL GRUNIL- 

